An-Najah Staff

The novel diamine–bis(ether–phosphine)ruthenium(II) complexes Cl2Ru(η1-Ph2PCH2 CH2OCH3)2(diamine)2(3L1–3L11) have been obtained by reaction of equimolar amounts of Cl2Ru(P∩O)2 (2) with the respective diamines L1–L11 in good yields. X-ray structural investigations of 3L2 and 3L8 show monoclinic unit cells with the space group P21/c. The octahedrally coordinated ruthenium atoms have each two trans-chlorides and cis-phosphines which is in agreement with NMR studies in solution. With the exception of 3L4 all mentioned ruthenium complexes are highly catalytically active in the hydrogenation of the α,β-unsaturated ketone trans-4-phenyl-3-butene-2-one. In most cases the conversions and selectivities toward the formation of the unsaturated alcohol trans-4-phenyl-3-butene-2-ol were 100% with high turnover frequencies under mild conditions. Novel diamine–bis(ether–phosphine)ruthenium(II) complexes have been prepared and characterized. X-ray structural investigations of 3L2 and 3L8 show monoclinic unit cells with the space group P21/c. These complexes are highly catalytically active in the hydrogenation of an α,β-unsaturated ketone, with excellent conversions and selectivities under mild conditions.

The novel diamine(dppp)ruthenium(II) complexes 3L1–3L12 have been obtained by reaction of equimolar amounts of Cl2Ru(dppp)2 (2) with the diamines L1–L12 in excellent yields. Within a few minutes one of the diphosphine ligands was quantitatively exchanged by the corresponding diamine. X-ray structural investigations of 3L1, 3L2, and 3L8 show triclinic unit cells with the space groups PView the MathML source (3L1, 3L2) and P 1 (3L8). Whereas in solution all these complexes prefer a trans-RuCl2 configuration, in the solid state cis-(3L1, 3L2) and trans-isomers (3L8) were observed. With the exception of 3L5, 3L6, and 3L12 all mentioned ruthenium complexes are highly catalytically active in the hydrogenation of the α,β-unsaturated ketone trans-4-phenyl-3-butene-2-one. In most cases the conversions and selectivities toward the formation of the unsaturated alcohol trans-4-phenyl-3-butene-2-ol were >99% with high turnover frequencies (TOFs) under mild conditions.

Treatment of RuCl2(η1-Ph2PCH2CH2OCH3)2(diamine) (1L1–1L7) with one equivalent of AgX (X=OTf, BF4) in CH2Cl2 results in the formation of the monocationic ruthenium(II) complexes [RuCl(η1-Ph2PCH2CH2OCH3)(η2-Ph2PCH2CH2OCH3)(diamine)]+X− (2L1–2L7). These complexes were characterized by NMR, and mass spectroscopy as well as by elemental analyses, 2L1 additionally by an X-ray structural analysis. Complex 2L1 crystallizes in the monoclinic space group C2/c with Z=8. The monocationic and neutral complexes were applied as catalysts in the selective hydrogenation of trans-4-phenyl-3-butene-2-one. With the exception of 1L3/1L7 and 2L3/2L7 all catalysts showed high activities and selectivities toward the hydrogenation of the carbonyl group under mild conditions. However, the activity of the cationic catalysts is only half of that of their neutral congeners.

The preparation of new three trans-[RuCl2(dppb)(N–N)] with mixed diamine (N–N) and 1,4-bis-(diphenylphosphino)butane (dppb) ligands, starting from RuCl2(PPh3)3 as precursor is presented. The complexes are characterized on the basis of elemental analysis, IR, 1H, 13C and 31P{1H}NMR, FAB-MS, TG/DTA and single crystal X-ray diffraction studies. Complex (2L1) crystallizes in the monoclinic unit cells with the space group P21. The catalysts are evaluated for their Cinnamic aldehyde hydrogenation. The catalysts show excellent activity and selectivity for the unsaturated carbonyl compound under mild conditions.